An aliphatic series polyisocyanurate preparation method includes the following steps: isocyanate and complex catalytic system formed by quaternary ammonium salt and inert alcohol solvent are added to a static mixer to lead isocyanate to have polymerization reaction, and then the formed product flow is transferred to a dynamic reactor for continuing the polymerization reaction; the reaction solution obtained in the polymerization reaction is processed by a second-level evaporator to obtain polyisocyanurate product. The preparation method can well control the reaction activity of the catalyst, causes the trimerization of isocyanate to be carried out in mild conditions and accordingly obtains tripolymer products with very high quality.